Skimming device



Feb. 8, 1949.

Filed June 30, 1945 JNVENTOR. THo/vms- WE. FOSTER Patented Feb. 8, 1 949 sirmmno DEVICE? r Thomas.mrsrme irempieca .calm ssor to TheRermtuientm Metals porporation, Oakland; Galifi, aooriiora'tion'--v of Delaware Appli caitibfl June 30', 194 5 602,58

This invention relates to" the casting: or ma'gnesium'. and. more: particularly to the: stepoat pour; ing: molten: magnesium into mold Magnesium castings made: m-er bypouriiig. molten magnesium; into molds and allowing ittto cool. therein without taking further precautions, generally have undesired characteristics. With present practice it is often difficult or impossibleto obtain castingsv withv the desired absence of included oxides, oxide skins, drossandlslagu The: cooled or solidified product having these included oxides, oxi'de' skins, dross and slag not being homogeneous and being stratifiedi or at least-differ?! ent atJdi-fferent parts thereof is aipi oducti ofi unde sirable and inferior quality? It has been found that where a proper separation or these oxides, oxide skins, dross and slag is accomplish'ed and, as far as possible, eliminating all turbulence in the metal as it enters the mold and having the flow as even as possible it is possible to obtain a more desirable product. Other difiiculties in casting molten magnesium are due to the low specific gravity of the magnesium, which can result in slag and other materials which are to be excluded from the casting not floating in nor on the metal but sinking therein, and they can enter the casting as a result.. Some attempts have been made to exclude the heavier substances, which have resulted in increasing the turbulence; An object of this invention is to minimize turbulence as the metal enters the mold and thereby minimize the disadvantages referred to above as being due thereto.

Another object of the invention is to separate from the metal entering the mold, foreign matter that is heavier than the molten magnesium. Further objects of the invention are to provide a simple and economical device that can be used in connection with conventional magnesium foundry equipment, either in addition thereto or built in as an integral part thereof.

Still further objects will be apparent on reading this specification in connection with the accompanying drawings.

On such drawings:

Fig. 1 is a vertical section of a casting assembly which includes the novel skimming fixture;

and

Fig. 2 is a perspective view of a modification of such fixture.

The invention can be used in connection with a conventional sand or other type of mold ll having the customary down sprue I! through which the molten metal enters the mold. The latter is shown as broken away since special fea- 5 Claims; (01. 22-134).

I tunes of. the: mold itselt, which may be conventional. or as desired; term; no part at this invent- Anon-ring: basim tit-which may be: round, angulan. or infact of preferred shape, and ma derof: sheet steehor of any other suitablemate rials isr locatedi overthe down sprue-to: feed: the molten metal thereinto; Y p

A skimming device I4 is placed-within therpoiming: basim. covering; the wholeportions 1 6 oi the basin: bottomareasadiacent the down spree, but not covering azver-y substantialapontioni H of such bottom area: The: fixture: may comprise a-i top wall Hi above and spacedifromthebasin: bottom; and; end wall t9; and side. walls It, the end and: side: walls supporting the wall; I18. A transverse slot. 22 isa provided at a level above thebasimbottom-, this-being: preferably in the. top: walla The: molten metal pouredi'firomq the sourceof supply 23 into:-thespace.- over the bottom ,area I! and the level rises as pouring continues until it is higher than the top of the skimming fixture. The metal then flows horizontally from the pouring space to and through the slot 22.

It should be poured at least as fast as it flows through the slot, in order to maintain a head of metal thereover so that any floating oxide and/or oxide skin will be prevented from passing therethrough. Substances which are heavier than the molten metal and which may be present I will be sunk to, and remain at, the bottom of the pouring space I! outside of the skimming device.

The device may have any desired shape, the only requirement with respect thereto being that the inlet opening 22 he at a higher level than the bottom of the space I! into which the metal is poured, and the metal be prevented fromentering into the space within the skimming device except through such inlet. It maybe made of .-baked core sand (Fig. 1.), sheet metal (Fig. 2.),

or any other suitable material.

The invention is well adapted for use in pourmetals where all of the material which it. is desired to exclude from the mold floats.

4. In a movable skimming device adapted to separate solid material from molten material being fed into the inlet spr-ue of a mold, a pouring basin comprising a walled enclosure, and a skimming device disposed within said enclosure and comprising a top wall intermediate the top and bottom of the pouring basin, said top wall being provided with an opening adapted to pass molten material from the pouring basin to the inlet sprue of the mold, and side walls supporting said top wall and cooperating therewith to form an open- 1. A movable pouring basin (ifimpri n em closed wall portion, and a skimming de gposed within said basin and comprising a top wall portion spaced above the bottom of said"- basin and provided with an inlet perforation and side walls supporting said top wall portion and cooperating with a part of said enclosed basin wall portion to form an open-bottom enclosure.

2. A movable, open-bottom pouring basin comprising a walled enclosure, and a skimming device disposed within said basin and comprising a top wall provided with an inlet perforation and spaced intermediate the top and bottom of the basin wall and side walls supporting said top wall and cooperating therewith 'to form an openbot'tom enclosure.

3. A movable, open-bottom pouring basin comprising a continuous enclosed wall portion of uniform height and even bottom edges, and a skimmingdevi-ce disposed withinsaid basin and comprisinga top wall portion spaced up from the bottom edges of said pouring basin, said top wall portion being provided with a slot adapted to pass molten metal from said basin downward, and side walls supporting said top wall and cooperating therewith and a portion of said basin wall to form an open-bottom enclosure.

bottom enclosure.

'5. In a movable skimming device adapted to separate solid material from molten metal being poured into the inlet sprue of a mold, a movable open-bottom pouring basin comprising a continuous enclosed wall portion of uniform height and level bottom edges, and a skimming device disposed within said basin and comprising a top wall portion spaced up from the bottom edges of said pouring basin, said top wall portion being provided with a slot adapted to pass molten metal from said basin downward to said inlet sprue, and side walls supporting said top wall and cooperating therewith to form an open-bottom enclosure.

THOMAS W. F. FOSTER.

REFERENCES CITED The following references are of record in the 

